In the latest wheel loaders, an engine torque is automatically switched to save fuel. For instance, a known method for saving fuel includes: judging whether or not a wheel loader is in an excavation operation and whether or not the wheel loader is ascending a hill; setting an engine in a high-power mode when the wheel loader is in the excavation operation or is ascending the hill; and setting the engine in a low-power mode when the wheel loader is neither in the excavation operation nor ascending the hill (see, for instance, Patent Literature 1).
Another known method includes: calculating a load on a working equipment pump and/or a load on a torque converter; and variably adjusting maximum output characteristics (torque curve) of an engine so that a maximum output torque of the engine available with a current engine speed exceeds the calculated load torque (see, for instance, Patent Literature 2).